The present invention relates to a leaf spring having a plurality of stacked spring leaves which contact one another, through intermediate plates or directly, only in a center clamping region and at their ends. The contact surfaces at the ends act as pairs of friction surfaces during the spring action.
Such a leaf spring is known from German Pat. No. 2,021,608. In the parabolic spring described therein friction plates which are disposed at the ends of the spring between each two spring leaves, form additional pairs of friction surfaces. This known arrangement has the drawback that the natural friction effected in this manner is not sufficient in all fields of application to dampen vibrations in vehicles with leaf spring suspensions. Thus, in case of railroad cars equipped with such parabolic springs, the danger exists that the wheels will jump off the tracks due to excessively high and insufficiently dampened vibration amplitudes of the car body. A further drawback of the known arrangement is that all friction forces depend on the operational load on the spring, since the frictional forces of the leaf spring surfaces which slide on one another are proportional to the forces with which the leaf spring surfaces are pressed against one another. Thus the springs may exhibit an altogether different behavior dependent on whether the car is in a loaded or in an empty state.